Charles F. Nahill Jr. quit yesterday as chairman of Montgomery County's fractious Republican Committee, ending a term that has seen the party lose much of its clout and its largest congressional seat.

Mary Shorley, the party's vice chairman and a county jury commissioner, will be acting chairman.

Within 30 days, she will call a convention of the 744 committee members to select a new chairman, Nahill said after a powwow with 40 to 45 party leaders at GOP headquarters in Norristown.

Among those who want the job are:

*Frank R. Bartle, a Lansdale attorney who lost a fight for the post to Nahill in 1990. He is a GOP area leader for Lansdale and a former Lansdale councilman.

*Robert J. Kerns, a Lansdale attorney who recently resigned as county solicitor.

*Del Rotelle, a GOP area leader for Upper Dublin and the wife of John Rotelle, head of Rotelle Inc. The firm is in the food business.

If it is clear after leaders meet with rank-and-file committee people that one person will get a majority of votes at the convention, the leaders hope everyone else will withdraw from the race, Nahill said.

Some in the party have called for Nahill's ouster in the wake of the GOP disaster in November's election and the party's other setbacks, both financial and political, last year.

But Nahill said he was not pressured to step down.

When he became chairman, he "had no concept of the pressures, the pulling and tugging and everything else," he said.

"There's a period of time beyond which if you stay you're not doing your job, you get burned out. Clearly, I was getting to the point where I was close to being burned out.

"No, I didn't feel any pressure to get out. I had nobody tell me I had to get out, and if they had and I didn't want to, I would have told them to drop dead anyway."

Nahill, who retired as a state legislator at the end of 1992, said he will work in marketing and government relations and his clients would prefer it if he were not the county's GOP chairman.

Nahill plans to do some lobbying in Harrisburg and needs to be able to deal well with people in both parties, he said.

In November, Republicans failed to carry the county for President George Bush, and the county lost the 13th Congressional District, its largest, to Democrat Marjorie Margolies-Mezvinsky, who defeated Republican Jon D. Fox.

Two of four other congressional districts that include parts of the county also went Democratic.

And a former Democratic county commissioner, Larry Curry, won the state House seat from which Nahill retired, the 154th District in Cheltenham.

In April, anti-abortion forces won four of the county's 15 seats on the state GOP committee, defeating candidates endorsed by the county GOP leadership.

The party's fund raising has declined, and the two major factions in the party have lost control of the county courthouse to a maverick Republican commissioner, Mario Mele, who has formed an alliance with the Democratic commissioner, Joseph M. Hoeffel.

Mele and Hoeffel have been dismantling what Hoeffel says is the patronage system that has traditionally been used to reward the Republican faithful with government plums.

But Nahill, who has campaigned for chairman twice on a pledge to unify the party, said no one pressured him to resign in the middle of his second term.

Former GOP chairmen, including Drew Lewis and Bob Asher, showed up at the meeting to give their advice on how the party can put itself back together and regain its full power.

Nahill said they and others at the meeting agreed that "personal agendas have to be put aside."

Frank Bartle is one person who has shown that the gap between the factions can be bridged, Nahill said.

Bartle backed former commissioners Paul B. Bartle and Floriana M. Bloss when they sought re-election against a challenge by Fox and Mele in 1991. In 1992, he headed Fox's congressional campaign.

And leaders at the meeting indicated that the bickering between Mele and the GOP hierarchy must cease.

Mele has been critical of Nahill, and many blame Mele for some of the party's problems. He wrested the chairmanship of the commissioners from Fox, whom GOP leaders had expected to be chairman.

Mele said it was the consensus of those at yesterday's meeting that it is "best for the party" that Nahill step down. He added that the "real problem" is not with the courthouse but with the GOP leadership.

Lawrence Coughlin, who retired as congressman for the 13th District in 1992, said after the meeting that the party "has got to raise money" and provide renewed leadership.

"We've been raising money, but not the way we had been. We've got to go back to raising the kind of money we used to," he said.

One way to restore that fund-raising capability is to make sure there is "a lot of respect for the Republican Party in the county," he said.